Robinia commemorates the French botanist Jean Robin (1550) and his son Vespasien who planted it in the Jardin des Plantes in 1634.
Pseudoacacia is from pseudo meaning false and Acacia the genus that it resembles.
Other Names:
Acacia (Europe)
False Acacia
Locust Tree (USA)
White Acacia
Summary:
A deciduous, thorny tree with an open crown that spreads by suckers and seed to form thickets up to 25 m tall. The leaves are light green, 20 to 30 cm long with 6 to 20 paired, egg shaped leaflets plus a terminal leaflet. The fragrant, white, pea-type flowers form reddish pods that are 7-10 cm long. It has deeply fissured bark.
Description:
Thorny deciduous tree
Cotyledons:
Two.
First leaves:
Leaves:
The leaves are light green, 20 to 30 cm long with 6 to 20 paired, egg shaped leaflets plus a terminal leaflet.
Stipules - 2 stout spines.
Petiole - Short.
Blade - of leaflet, egg shaped, 15-30 mm long, shortly stalked.
Stems:
Up to 25 m tall, branched. Thorny stems and branches.
Dark furrowed bark.
Sapwood is ring porous.
Flower head:
Long, drooping raceme from the axils of leaves.
Flowers:
White, fragrant, pea type flowers.
Ovary - Many ovules
Stigma - Terminal
Style - not bearded.
Calyx - bell shaped, 7 mm long, almost two lipped, 5 unequal, broad lobes. Hairy.
Petals - Standard almost round, bent back. Keel incurved. Standard, wings and keel 18 mm long
Stamens - 10. Upper stamen free other 9 united.
Filaments - Thread like.
Anthers - Without glands.
Fruit:
Reddish, long, flattened, drooping pod. 70-100 mm long by 12-14 mm wide, straight edged, upper join narrowly winged. Hairless.
Seeds:
No fleshy appendage (caruncle)
Roots:
Forms suckers especially if damaged.
Key Characters:
Tree
Leaves imparipinnate
Flowers, pea type, racemose
Many ovules.
Style not bearded
Anthers without glands.
Pod oblong compressed, rather broad, 2 valved, dehiscent, not breaking transversely into articles.
Adapted from John Black.
Biology:
Life cycle:
Deciduous tree. Forms suckers especially if roots are damage. Seedlings are rare. Sets seed when 6 years old.
Physiology:
Intolerant of shade and water logging.
Reproduction:
By seed and suckers.
Flowering times:
Spring to early simmer in western NSW.
Seed Biology and Germination:
Vegetative Propagules:
Forms suckers and stems coppice especially if damaged.
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
Spreads by seeds and sprouts from the roots forming dense stands displacing native vegetation. Most long distance spread is by intentional plantings.
Origin and History:
Mexico, North America.
Distribution:
ACT, NSW, QLD, SA, VIC, WA.
Habitats:
Common in waterways.
Climate:
Temperate.
Soil:
Sands, slightly calcareous soils.
Plant Associations:
Significance:
Beneficial:
Ornamental. Honey. Fixes nitrogen.
Strong, hard, heavy durable timber used for tool handles, railway sleepers, posts and fuel.
Used as a street tree and shelter around farm houses and for erosion control on coastal dunes.
Leaves and pods edible but can be toxic
Detrimental:
Weed of disturbed woodlands, roadsides, waterways.
Forms thorny thickets.
Invasive weed of the USA.
Toxicity:
The seeds, leaves and bark are toxic.
The honey from it may also be toxic.
Symptoms:
Treatment:
Legislation:
None.
Management and Control:
Plant tall growing native species to reduce the levels of light.
Thresholds:
Eradication strategies:
Cut down the tree and paint the stump with neat glyphosate to reduce regrowth and suckering. Spray regrowth and suckers when they are about 500 mm tall with glyphosate.
It re grows vigorously from cut roots and stumps and these sprouts need to be removed continually to exhaust the root system.
Access, Grazon and metsulfuron are worth a trial.
Herbicide resistance:
None reported.
Biological Control:
Related plants:
No other weedy species in the genus.
Plants of similar appearance:
Tagasaste
Tree of Heaven
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne).P168. Photos.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P465.
Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P411. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P156. Photo.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #858.1
Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P40. Photo.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.